The use of pneumatic spun fiber collecting systems on spinning frames and similar textile machines has been standard procedure in the textile industry for a long time. In such fiber collection systems, ducting extends throughout the length of the spinning frame with inlets for loose fibers under each delivery position along the machine. A motor driven fan creates suction in the ducting system and fibers are drawn into the system and delivered to a large collection box at one end of the spinning frame equipped with a screen which prevents the exhausting of loose fibers back into the spinning room. Such fiber collection systems are very well known and are disclosed by U.S. Pat. Nos. 2,431,762; 2,672,733; 2,774,061; 2,812,632; and others.
The most commonly used pneumatic fiber collection systems for spinning machines, particularly the exhausts thereof, are extremely noisy, commonly exceeding 96 decibels on the "A" Scale Fast Response. Existing Federal laws administered under the Occupational Safety Health Administration (OSHA) require maintaining the noise level below 90 decibels on the "A" Scale Fast Response. It is the primary objective of this invention to meet this requirement without rendering the existing pneumatic fiber collection system ineffective due to the creation of back pressure in the system.
Prior art attempts to suppress the noise of pneumatic fiber collection systems on spinning frames have tended to reduce the effective suction in the systems to such low levels that the systems are substantially useless. Additionally, because various systems or units possess differing predominant noise frequencies, it has not been possible to devise a muffler or noise suppressor which can be universally employed on most or all spinning frames, and it is not economically feasible to construct a customized noise suppressor of a given size and configuration for each machine.
The present invention has the ability to overcome these main problems of the prior art through the provision of an easily adjustable or tunable noise suppression device which can be fitted to the exhaust of any spinning machine fiber collection box to maintain the level of noise generated by such exhaust at acceptable levels while maintaining the necessary degree of suction in the pneumatic fiber collection system for full and efficient operation. The adjustable noise suppression device embodied in the invention can be variably tuned in a very convenient manner to reduce noise generated by a predominant sensitive wave length present at the exhaust of any given pneumatic fiber collection system. The tuning or adjusting of the device is also effective to increase or decrease the degree of suction in the system so that the suction does not fall below acceptable levels because of back pressure created by the suppression device. In this respect, the invention is extremely versatile in its adaptability to a wide variety of textile machines which possess varying noise characteristics, thus obviating the necessity for expensive customizing of equipment.
To comply with the duty to disclose known prior art under 37 C.F.R. 1.56, the following prior U.S. Pat. Nos. are made of record herein:
2,112,608;
2,514,344;
2,708,829;
2,958,387;
3,219,143;
3,435,911;
3,438,522;
3,895,686;
3,986,325;
4,015,683; 4,024,698.